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After the occurrence of barrier lakes, a disaster chain involving a dam breach is easily established, and it is vital to develop a quick quantitative risk assessment approach based on limited data. This method creates a rapid quantitative evaluation model of a dam-breach disaster by rapidly getting the three-dimensional geographic information of the impacted area of the barrier lake. A refined and simplified stability quick evaluation has been achieved based on the particle size composition of the dam body of the barrier lake. The rapid analysis of the peak flow process and evolution process (within 1 hour) has been realized based on the breach mechanism, erosion characteristics and the collapse process. The function of risk population and life loss has been established based on the extreme learning machine network model, and the early warning of life loss distribution characteristics has been realized. The disaster chain effect of a dam-breach disaster has been clarified. Applying it to the example of Tangjiashan barrier lake, it is found that this method can better warn the breach disaster chain. The excavation of a drainage groove can reduce the peak flow, the maximum flow velocity, breach width, and breach storage capacity of the barrier lake, but cannot prevent the breach. If the drainage groove is not excavated, the breach storage capacity will reach 3.14×108 m³, the breach peak flow will reach 9 343.35 m³/s, and the breach top width will increase to 151.6 m. The excavation of the drainage groove can reduce the breach peak flow by 12.6%, the breach storage capacity by 36.5%, and the breach risk of the barrier lake. When the early warning time exceeds 2 hours, the life loss rate can be reduced to zero by evacuating the residents in the downstream submerged area. This method can realize rapid quantitative risk assessment in emergency disposal of barrier lakes and provide technical support for emergency disposal decisions. [ABSTRACT FROM AUTHOR]